Catalyst – October (2x[2+4]), 2009



Don’t forget to make
your Weekly Goal!
Monday Mystery
Element
Discovered by
boiling urine
There are 2 forms:
white and red
The white forms
combusts in air
Catalyst – October (2x[2+4]), 2009


PHOSPHORUS!

Monday Mystery
Element
Discovered by
boiling urine
There are 2 forms:
white and red
The white form
combusts in air
Today’s Agenda
Catalyst
 More secrets of the PT: Valence
Electrons, Atomic Size, and
Electronegativity
 Group Work Time
 Exit Question

Today’s Objectives

SWBAT determine periodic trends
for valence electrons, atomic size,
and electronegativity.
Valence Electrons
Don’t forget!
 Valence electrons are the
electrons in the outermost energy
level.
Example



Electron configuration for silicon (Si):
What is the highest energy level?
So how many valence electrons?
2
2
6
2
2
1s 2s 2p 3s 3p
2 + 2 = 4!
Group Challenge

Each group will write electron configurations for the
elements in ONE family. Then, count the number of
valence electrons for each configuration.
 Group
1:
 Group 2:
 Group 3:
 Group 4:
 Group 5:
 Group 6:
 Group 7:
 Group 8:
Alkali Metals
Alkaline Earth Metals
Boron’s Group
Carbon’s Group
Nitrogen’s Group
Halogens
Noble Gases
Noble Gases
Group Challenge

Each group will write electron configurations
for the elements in ONE family. Then, count
the number of valence electrons in each
configuration.
 Group
1:
 Group 2:
 Group 3:
 Group 4:
 Group 5:
 Group 6:
Alkali Metals
Boron’s Group
Carbon’s Group
Nitrogen’s Group
Halogens
Noble Gases
Valence Electrons
What is Atomic Size?

Atomic size is…
How big an atom is
Also known as atomic radius
Graphing Atomic Size (Radii)

Draw 2 line graphs
X-axis:
Element
Y-axis: Atomic Radius (picometers)
Elements and their Atomic Radii (1)
1 picometer = 1 x 10-12 m
Element
Atomic Radius (picometer)
Hydrogen
37
Lithium
152
Sodium
186
Potassium
227
Rubidium
248
Cesium
265
Elements and their Atomic Radii (2)
1 picometer = 1 x 10-12 m
Element
Atomic Radius (picometer)
Lithium
152
Beryllium
112
Boron
85
Carbon
77
Nitrogen
75
Oxygen
73
Fluorine
72
Neon
71
Atomic Size – Graph 1
Atomic Radius (picometer)
350
300
250
200
150
100
50
0
0
1
H
2
Li
3
Na
4
K
Element
5
Rb
6
Cs
7
Atomic Size – Graph 2
Atomic Radius (picometer)
160
140
120
100
80
60
40
20
0
0
Li
2
Be
B
C4
6
N
O
Element
F
8
Ne
10
What trend(s) do
you notice?
Atomic size DECREASES as you go across the Periodic Table
Atomic size INCREAESES as you go down the
Periodic Table
Atomic Size
Key Point #1: Atomic size increases as
you go down the periodic table and
decreases as you go left to right across
the periodic table.
Practice Problems

Rank the following elements in order of
increasing atomic size based on location on
the periodic table (smallest to biggest)
Fr, Sc, P, Pd
P, Pd, Sc, Fr
F, As, Tl, S
Fluorine, Sulfur, Arsenic, Thallium
Practice Time!
1.
2.
3.
T or F? Atomic size decreases as you move right across
the periodic table.
T or F? As you move down the Periodic Table, atoms get
smaller.
Rank the following sets of elements in order of increasing
atomic size (small  big).
Set A: Bh, Mn, Re, Tc
Set C: Y, Ti, Sg, Ta
4.
Set B: Sb, I, Ag, Ru
Rank the following sets of elements in order of
decreasing atomic size (big  small).
Set A: Cl, At, I, F, Br
Set B: Te, Xe, Sn, In
Set C: Rb, K, Sr, Ca
What is electronegativity?

Electronegativity is…
The ability of an atom to attract
electrons to itself in a chemical
bond
How much an atom wants
electrons
Graphing Electronegativity

Draw 2 line graphs
X-axis:
Element
Y-axis: Electronegativity (Paulings)
Elements and their Electronegativity (1)
Element
Electronegativity (Paulings)
Hydrogen
2.20
Lithium
0.98
Sodium
0.93
Potassium
0.82
Rubidium
0.82
Cesium
0.79
Francium
0.70
Elements and their Electronegativity (2)
Element
Electronegativity (Paulings)
Lithium
0.98
Beryllium
1.57
Boron
2.04
Carbon
2.55
Nitrogen
3.04
Oxygen
3.44
Fluorine
3.98
Electronegativity Graph 1
2.5
Electronegativity
2
1.5
1
0.5
0
0
1
2
3
4
Element
5
6
7
8
Electronegativity Graph 2
Electronegativity
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0
2
4
Element
6
8
What trend(s) do
you notice?
Key Point – Atomic Size
Key Point #1: Atomic size increases as
you go down the periodic table and
decreases as you go left to right across
the periodic table.
Electronegativity Trends
Electronegativity
Key Point #2: Electronegativity
decreases as you go down the periodic
table and increases as you go left to
right across the periodic table.
Practice Problems

Rank the following elements in order of
increasing electronegativity based on location
on the periodic table (smallest to biggest)
Mg, Sr, Be, Ra
Radon, Strontium, Magnesium, Beryllium
Cl, Si, Al, S, P
Aluminum, Silicon, Phosphorus, Sulfur, Chlorine
Practice Time!
1.
2.
3.
T or F? Electronegativity decreases as you move left
across the periodic table.
T or F? As you move down the Periodic Table, atoms get
more electronegative.
Rank the following sets of elements in order of increasing
electronegativity (small  big).
Set A: Bh, Mn, Re, Tc
Set C: Y, Ti, Sg, Ta
4.
Set B: Sb, I, Ag, Ru
Rank the following sets of elements in order of
decreasing electronegativity (big  small).
Set A: Cl, At, I, F, Br
Set B: Te, Xe, Sn, In
Set C: Rb, K, Sr, Ca
How does atomic size related to
electronegativity?
Key Point #3: Atomic size is indirectly
related to electronegativity.
ATOMIC SIZE
As electronegativity
ELECTRONEGATIVITY
increases, atomic size
decreases!
Why is this relationship true?
Atoms with HIGH ELECTRONEGATIVITIES hold
their electrons very close!
 Sooooo, the atomic size decreases

High or low electronegativity?
Large or small atomic size?
Group Work Time!
Bohr Models
Electron Confuguration
Rank by Atomic Size and
Electronegativity
Similarities
Decorate and be creative!
Exit Question
1.
2.
3.
Which element has atoms with the
smallest size: Cl, Se, P, or F?
Which element has the largest
electronegativity: Ag, Cu, Hg, or
Zn?
As electronegativity increases,
atomic size….?